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tls.h

tls.h 2.6 KB
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  1. /* Definition for thread-local data handling.  Generic version.
    2. 

  2.    Copyright (C) 2002 Free Software Foundation, Inc.
    3. 

  3.    This file is part of the GNU C Library.
    4. 

  4. 

  5.    The GNU C Library is free software; you can redistribute it and/or
    6. 

  6.    modify it under the terms of the GNU Lesser General Public
    7. 

  7.    License as published by the Free Software Foundation; either
    8. 

  8.    version 2.1 of the License, or (at your option) any later version.
    9. 

  9. 

  10.    The GNU C Library is distributed in the hope that it will be useful,
    11. 

  11.    but WITHOUT ANY WARRANTY; without even the implied warranty of
    12. 

  12.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13. 

  13.    Lesser General Public License for more details.
    14. 

  14. 

  15.    You should have received a copy of the GNU Lesser General Public
    16. 

  16.    License along with the GNU C Library; if not, see
    17. 

  17.    <http://www.gnu.org/licenses/>.  */
    18. 

  18. 

  19. /* By default no TLS support is available.  This is signaled by the
    20. 

  20.    absence of the symbol USE_TLS.  */
    21. 

  21. #undef USE_TLS
    22. 

  22. 

  23. 

  24. /* An architecture-specific version of this file has to defined a
    25. 

  25.    number of symbols:
    26. 

  26. 

  27.      TLS_TCB_AT_TP  or  TLS_DTV_AT_TP
    28. 

  28. 

  29.      The presence of one of these symbols signals which variant of
    30. 

  30.      the TLS ABI is used.  There are in the moment two variants
    31. 

  31.      available:
    32. 

  32. 

  33.      * the thread pointer points to a thread control block
    34. 

  34. 

  35.      * the thread pointer points to the dynamic thread vector
    36. 

  36. 

  37. 

  38.      TLS_TCB_SIZE
    39. 

  39. 

  40.      This is the size of the thread control block structure.  How
    41. 

  41.      this is actually defined depends on the ABI.  The thread control
    42. 

  42.      block could be internal descriptor of the thread library or
    43. 

  43.      just a data structure which allows finding the DTV.
    44. 

  44. 

  45.      TLS_INIT_TCB_SIZE
    46. 

  46. 

  47.      Similarly, but this value is only used at startup and in the
    48. 

  48.      dynamic linker itself.  There are no threads in use at that time.
    49. 

  49. 

  50. 

  51.      TLS_TCB_ALIGN
    52. 

  52. 

  53.      Alignment requirements for the TCB structure.
    54. 

  54. 

  55.      TLS_INIT_TCB_ALIGN
    56. 

  56. 

  57.      Similarly, but for the structure used at startup time.
    58. 

  58. 

  59. 

  60.      INSTALL_DTV(tcb, init_dtv)
    61. 

  61. 

  62.      This macro must install the given initial DTV into the thread control
    63. 

  63.      block TCB.  The normal runtime functionality must then be able to
    64. 

  64.      use the value.
    65. 

  65. 

  66. 

  67.      TLS_INIT_TP(tcb, firstcall)
    68. 

  68. 

  69.      This macro must initialize the thread pointer to enable normal TLS
    70. 

  70.      operation.  The first parameter is a pointer to the thread control
    71. 

  71.      block.  The second parameter specifies whether this is the first
    72. 

  72.      call for the TCB.  ld.so calls this macro more than once.
    73. 

  73. 

  74. 

  75.      THREAD_DTV()
    76. 

  76. 

  77.      This macro returns the address of the DTV of the current thread.
    78. 

  78.      This normally is done using the the thread register which points
    79. 

  79.      to the dtv or the TCB (from which the DTV can found).
    80. 

  80.   */
    81.